PRE-TREATMENT OF ORGANIC LIQUID WASTE STREAM AT CERNAVODA NPP Gabriela Teodorov, Laszlo Toro, Adina Sandru MATE-FIN, Bucharest, Romania Dennis Kelley Pacific Nuclear Solutions, Indianapolis, USA Dorin Dumitrescu NPP Cernavoda, Romania 1

Presentation outline Cernavoda NPP radioactive waste streams The Nochar polymer Management of the Cernavoda NPP organic liquid waste – project performed by Mate-Fin Solidification at a small (laboratory) scale Solidification at a large scale Conclusions 2

Cernavoda NPP radioactive waste streams (1) Cernavoda NPP – two CANDU®6 single units Pressurized Heavy Water Reactors (PHWR) Main sources of radioactive waste Primary Heat Transport (PHT) systems Moderator systems Other sources of radionuclides Wastes are segregated according to source (reactor building or service building) and type of material

Cernavoda NPP radioactive waste streams (2) Spent resins Spent filter cartridges Solid waste Type 1 solid waste (contact gamma dose rate < 2 mSv h-1) Type 2 solid waste (contact gamma dose rate between 2 mSv h-1 and 125 mSv h-1) Type 3 solid waste (contact gamma dose rate higher than 125 mSv h-1) Liquid radioactive wastes Aqueous liquid wastes Organic liquid wastes

Cernavoda NPP radioactive waste streams (3) Organic liquid wastes Lubricating oil from pumps and turbines In contact with the reactor primary coolant and moderator tritium up to about 109 Bq kg-1 small quantities of radionuclides such as Co-60, Nb-95, Zr-95, Cs-137 Spent solvents from decontamination area, laboratories and maintenance activities white spirit, ethylene glycol, alcohol ethyl, toluene, chloroform, and acetone

Cernavoda NPP radioactive waste streams (4) Organic liquid wastes (contd.) Liquid scintillation cocktails Sampling of the Moderator and PHT system and their auxiliary systems, liquid effluent systems Mainly contaminated with tritium, segregated by tritium content Spent solvents from decontamination area, laboratories and maintenance activities white spirit, ethylene glycol, alcohol ethyl, toluene, chloroform, and acetone

Cernavoda NPP radioactive waste streams (5) Organic liquid wastes (contd.) Radioactive sludge from maintenance activities on the active drainage system contaminated with gamma nuclides Flammable solids mixture of solid materials (textile and plastic) and oils from maintenance activities contaminated with gamma nuclides and 3H Collected at waste collection points in special canisters Placed for intermediary storage in specially constructed 220l stainless steel drums

The Nochar® polymer (1) Synthetic absorbent system consists of a range of granulated polymer - immobilize liquid materials through a combined absorption and inter-molecular bonding process bonds the organic liquid into a soft, spongy, rubber-like material the polymer crystals can be specifically designed to address the characteristics of given mixed organic liquid waste fast solidification: varies between 1 hour and 48 hours, depending on the type of waste 8

The Nochar® polymer (2) Stability of Nochar no chemical reaction no heat build-up or heat release from the resulted solid waste no leaching; organic liquids are linked and secure in the polymer structure Possibility to blend polymers to solidify various types of liquid waste; polymers are hydrophobic an hydrophilic Polymerized solid waste reduce the risk of fire Acceptable volume increase – a factor of 1.3-1.5 It can immobilize LLW, ILW and HLW It remains solid for more than 10,000 years 9

Management of the Cernavoda NPP organic liquid waste – project performed by Mate-Fin (1) Solidification of all organic liquid waste by absorbing the liquid into the organic polymer structure. The main reason is a requirement of the regulatory body not authorising the existence of inflamable liquid waste in the interim solid waste storage facility The polymers used for this purpose are NOCHAR Petrobond® for organic liquid waste and NOCHAR Acidbond® for aqueous wastes. Why NOCHAR polymer? Bound the water, prevent migration of HTO or T2O Permit further treatment (ex. incineration) The technology used for organic liquids provides near each mixture of NOCHAR Petrobond® and NOCHAR Acidbond® layer two safety layers of NOCHAR Acidbond® polymer at the base and upper part of the storage drum. 10

Management of the Cernavoda NPP organic liquid waste – project performed by Mate-Fin (2) Solid-liquid mixtures are treated with NOCHAR Petrobond® organic polymer, the organic liquid (mainly oil) is solidified and separated mechanically from the solids The remaining solids (plastics and/or textiles) do not contain organic liquid and can be treated as “normal” solid waste. The technology developed by MATE-FIN at Cernavoda to perform the separation is based on a "sandwich" structure of solid and absorbent polymer. 11

Solidification at a Small Scale (1) A total of about 20 organic liquid waste sub streams (oils, scintillation liquids and solvents) have been tested by MATE-FIN in the experimental campaign, at the end of 2008. The polymers used were Nochar N910 Petrobond® and N960 Acidbond®. N910 is suitable for hydrocarbon waste streams and N960 for acid, alkali and aqueous waste stream The polymers are blended if a mixed hydrocarbon/aqueous waste stream is encountered. Average volume increase after solidification was between 1.3-1.5 depending on the liquid to be solidified 12

Solidification at a Small Scale (2) A stratificated structure was realized to assure higher contact between the polymer and the liquid to be solidified 13

Solidification at a Small Scale (3) 14

Solidification at a Small Scale (4) Experimental results Test 1 Type of waste: Pump oil Formula for polymers: Petrobond (95%) and Acidbond (5%); polymers are blended manually Bonding ratio = 1:2,5 Time for solidification: 24 hours Result = good solidification Test 2 Type of waste: oil (80%) with water (20%) Formula for polymers: Petrobond (84%) and Acidbond (16%); polymers are blended manually Bonding ratio: 1:2,2 Result= good solidification 15

Solidification at a Small Scale (5) Experimental results Test 3 Type of waste: Scintillation fluid Formula for polymers: Petrobond (10%) and Acidbond (90%); polymers are blended manually Bonding ratio: 1:2 Time for solidification: 24 hours Result = good solidification Test 4 Type of waste: Solvents Formula for polymers: Petrobond (10-12%) and Acidbond (90- 88%); polymers are blended manually Bonding ratio: 1:2,1 Time for solidification: 48 hours Result: good solidification 16

Solidification at a Small Scale (6) Conclusions The results of the experimental campaign illustrate that the Nochar N910/N960® polymer systems have proved to be effective in the immobilization of organic liquid waste streams into a solid polymeric product, with no leakage of liquid at compression. A key point arising from this experimental campaign: For the large scale project there is the need to test for compatibility and to assess the correct organic liquid waste/ polymer ratio on a case by case basis. 17

Solidification at a Large Scale (1) On the basis of the results of this experimental campaign, MATE-FIN started the solidification of organic liquid waste from Cernavoda NPP at the beginning of 2009. The method used by MATE-FIN’s specialists consist of the following important steps: The contaminated organic liquid waste and the polymer was pre- weighed, to obtain the proper bonding ratio; The materials (organic liquid and polymer) were mixed at a pre- determined slow speed in order to avoid polymer breaking; The solidified organic liquid was packed into drums and allowed to cure for 24-48 hours; The solidified organic liquid was packed in PE bags (10-12kg) and re-packed in 220L drums, type A containers, ready for transport to incineration operator. 18

Solidification at a Large Scale (2) 19

Solidification at a Large Scale (3) 20

Solidification at a Large Scale (4) Lessons learned A safety layer of N910 (6-7 cm) and N960 (3cm) at bottom of the drum is very important, N960 will to capture the 3H as tritiated water. A safety layer at top of the drum (N910 and N960) have to be placed. The mixture of N910 and N960 should be blended well prior to loading into the drum. The speed of mixing of the organic liquid and polymer is critical, the optimal mixing speed is up to 15-20rpm. The key point is to have good liquid and polymer touch, over mixing can damage the polymer. Loading the 1st layer of polymer (on top of the safety layer) avoid to compress the polymer. Check the 1st batch of oil (even it seems to be from pumps), if there is a water phase at the bottom of the oil drum the polymer formula have to be changed for the 1st layer of polymer 21

Solidification at a Large Scale (5) Lessons learned The composition of liquid scintillation cocktails is about 10% water and 90% Ultima Gold, there is a possibility the water is phasing out, as older the scintillation liquisd is, the more likely is the appearance of bi-phase streams. There a re two possibilities: stir/mix (emulsify) the entire drum of scintillation fluid prior to solidification, add more N960 in the 1st layer of polymer, 75% - N910 and 25% - N960 is optimal (more N960 is required to immobilize the water). Mixing will be required in the case of scintillation liquid, solidification occurs very quickly, causing a “skin” or top layer solidification, the “skin” does not allow the liquid to penetrate the polymers on its own (via gravity). The best is to solidify in small batches and after mixing in the final drum. 22

Organic liquid separation from solid-liquid mixture 23

CONCLUSIONS Nochar® polymer systems were effective in the immobilization of organic liquid and inflammable waste from NPP Cernavoda resulting a stable non inflamable solid; During the experimental campaign MATE-FIN established the appropriate organic liquid to polymer ratios depending on type of the waste (oil, solvents, scintillation liquid); During 2 years of project all inflammable liquid wastes were removed from the Intermediate Radioactive Waste Storage Facilities from Cernavoda NPP, without significant waste volume increase . 24

THANK YOU FOR YOUR ATTENTION! QUESTIONS 25